All-terrain vehicles propelled by an endless loop track include suspension systems for attaching the track to the body of the vehicle. Previous suspension systems have suffered from one or more of the following problems: poor ride for occupants of the vehicle, poor handling of the vehicle while turning, poor load carrying capability, tendency to accumulate mud and debris, complicated maintenance, particularly if a break-down occurs in a remote location, lack of suitability for operation on both land and water (amphibious operation). Many of these problems are exacerbated when the vehicle is operated at high speeds. There remains a need for an all-terrain vehicle propelled by an endless loop track that is capable of ameliorating one or more of the aforementioned problems, particularly one that is suitable for operation at high speeds and/or in amphibious conditions.